Artificial ankle



July 24, 1962 M. M. BAIR ARTIFICIAL ANKLE 5 Sheets-Sheet 1 Filed March 4, 1959 INVENTOR.

MILFORD M. BAIR Maw ATTORNEY.

July 24, 1962 BAlR 3,045,247

ARTIFICIAL ANKLE Filed March 4, 1959 5 Sheets-Sheet 2 62 INVENTOR.

- MILFORD M. BAIR BY FIG. 5 M 73% ATTORN E'Y.

July 24, 1962 M. M. BAIR ARTIFICIAL ANKLE 5 Sheets-Sheet 5 Filed March 4, 1959 mm mm INVENTOR. MILFORD M. BAIR ATTORNEY.

July 24, 1962 M. M. BAlR 3,045,247

ARTIFICIAL ANKLE Filed March 4, 1959 5 Sheets-Sheet 4 BY x66 W/O wy FIG. 9 ATTORNEY.

July 24, 1962 I M. M. BAIR 3,045,247

ARTIFICIAL ANKLE Filed March 4, 1959 5 Sheets-Sheet 5 INVENTOR. MILFORD M BAIR FIGII BY ATTORNEY.

' atent 3,045,247 Patented July 24, 1962 3,045,247 ARTIFICIAL ANKLE Milford M. hair, Bonita Springs, Fla. Filed Mar. 4, 1959, Ser. No. 797,092

18 Claims. (Cl. 3-32) This invention relates to an artificial ankle for belowknee amputees.

'I he desideratum of this invention is to provide amputees, more particularly those whose limbs have been amputated below the knee, with a prosthesis or artificial ankle that simulates the movements of a human ankle.

Although there have been many attempts to provide amputees with prosthetic devices that will enable them to move about with a reasonable degree of assurance and self-confidence, there is an extreme lack or absence of ankle prosthesis that will provide the amputee with the degree of movement and support that most nearly approximates the mechanical operation and manipulations that are capable of being performed by a human ankle.

To this end it is an object of the present invention to provide an artificial ankle or prosthesis for below-knee amputees that will simulate the operation and degree of movement of a human ankle.

It is another object of the present invention to provide an artificial ankle having simulated leg and foot parts that are movable relative to each other in a forward and aft direction in the same manner that one with a human ankle may manipulate the foot to raise or lower the toe at varying inclined angles with respect to his leg.

Still another object of the invention is to provide an artificial ankle for amputees that will provide the wearer with the same sense of security and assurance of complete stability when performing all manners of locomotion as one having a human ankle.

A further object of the invention is to permit the use of' the artificial ankle on lateral or forward and aft inclined walking surfaces, and to enable the wearer thereof to sit with his legs extended before him in a position of repose or relaxation with the full knowledge and realization that the inventive artificial ankle described hereinafter will permit him to place his foot or shoe fiat upon the ground or walking surface in the same manner as any other person having anormal functioning human ankle.

Other and further objects of my invention reside in the structures and arrangements hereinafter more fully described with reference to the accompanying drawings in which:

FIG. 1 is a partial perspective view of the inventive ankle constructed in accordance with the teaching of the invention and showing certain portions thereof in sections.

FIG. 2 is a partial side view of the invention with the Weight of the wearer applied. thereto and showing the simulated leg and foot in standingposition or with the leg at right angles substantially perpendicular to the walking surface.

FIG. 3 is a section of FIG. 2 taken along lines Zia-3.

FIG. 4 is a view of the leg shown in FIG. 2 in the direction of lines 44 showing the structural arrangement of elements of the inventive ankle with the weight of the wearer removed therefrom.

FIG. 5 is a view similar to FIG. 2 with the weight of the wearer removed from the ankle and with parts thereof shown in section.

FIG. 6 is a view of the parts shown in FIG. 5 when the weight of the wearer is applied to the ankle.

/ FIG. 7 is side view of the damper and limiting structures.

FIG. 8 is a perspective view of a portionof the structure in FIG. 7.

FIG. 9 is a sectional View of parts of the ankle when the leg is positioned forward of the wearer and the sole of the shoe is flat upon walking surface. 7

FIG. 10 is a sectional view of parts of the ankle when negotiating an inclined surface.

FIG. 11 shows the lower clutch portion of the ankle when the shoe is on a laterally inclined surface, and

FIG. 12 is a perspective view of the pawl.

Referring now to the drawings, the prosthesis or artifioial ankle of the present invention is generally identified by the numeral 20. The artificial ankle 20 comprises a simulated leg 22 that may be constructed in any known manner to have a legskin 24 on which an exterior surface 26 simulates the color and contour of a human leg. The leg 22 is movably related to an artificial foot generally identified by the numeral 28.

In the drawings the foot 28 is represented as a shoe that may be especially constructed to flex and provide the appearance of a covering for a normal foot. The foot or shoe 28 is connected with the leg 22 for relative forward and aft pivotal movement by a mechanism generally identified by the numeral 30 presently to be described. It is the function and purpose of the mechanism 30 to enable the wearer to place his foot solidly upon the ground or other walking surface in the same manner as the human ankle permits one to place his foot on irregularly contoured surfaces when standing or walking.

In the past, it has been a problem and a defect in prosthetic devices in that the wearer of an artificial leg could not place the sole of his shoe flat upon the ground or Walking surface if such surface had any irregular contours. Further defects in such devices have been in the inability of the wearer thereof to sit in a slouching position with his artificial limbs extended before him While placing the sole of hisshoe fiat upon the ground in the same manner as a person having a normal functioning ankle.

The forward and aft movement mechanism 30 of the present invention permits the wearer of the ankle 21 to place the sole of his foot or shoe 23 flat upon the walking surface when reclining or sitting in a slouched position or when Walking on irregularly contoured surfaces. The mechanism 30 serves to provide a connection between the artificial leg 22 and the foot or shoe 28 for their relative forward and aft pivotal movements about a common axis, and in addition thereto, for displacement with respect to each other.

To understand the operation of the mechanism 353 more fully let us refer now to the drawings wherein there is disclosed a pin or pivot means 32. The pin or pivot means 32 defines a common pivot or axis about which the leg and shoe 22 and 28 are pivotally movable with respect to each other. The pivot means 32 is mounted for lost-motion displacement within elongated slots 34 delined in opposite sides 36 and 33 of a leg' casing construction more clearly shown in FIGS. 1, 2, 5, 6, 9 and 10. The leg casing, comprising the laterally or oppositely disposed spaced sides 36 and 38, is secured in the simulated leg 22 in any suitable manner as to be fixed for movement therewith.

In the present invention the casing comprising the sides 36 and 38 are secured at theirtops to cross brace or bulkhead 44) that may be welded at 42 to the interior of the leg. Upstanding anchor pins 44 projecting from the tops of'the sides 36 and 38 may be suitably fastened to the cross brace 40. The casing is limited from movement relative to the interior of the leg 22 by further forward and aft brackets 46 and 48. It may be said that the casing sides 36 and 33 are mirror images of each other and as such the elongated slot 34 is provided in each of these sides for guiding movement of the pivot pin 32 within the length of the slot. It will be noted from the 3 drawings that the slot 34 defined in each of the sides of the casing is directed at a slightly inclined angle relative to the leg when the leg is positioned substantially perpendicular to a level walking surface. This may be seen more clearly in FIGS. 2, 2, 5, and 6.

An engaging means or clutch 50 is mounted at 52 between the sides 36 and 38 of the casing and to the aft bracket 48 for fixed movement with the leg 22. The clutch 50 describes a conical segment of an elongated are having an inverted V-shape in cross-section and performing the function of a female clutch member. The extent of the arc of the female clutch 50 is predetermined to permit relative movement of the leg and shoe substantially equal to the extent of tilting or pivoting movement that the human foot may perform with respect to a leg in a normal functioning human ankle.

Although, throughout the description of the present invention, the mechanism 30 and the relative pivotal movement described with respect to the leg and shoe is termed forward and aft" this terminology is intended to describe the same movement that may be performed by a human ankle when the foot is tilted or pivoted back and forth into different angles with respect to the leg. The term forward and aft has been here selected in preference to the term tilting because the shoe 28 and the leg 22 are not completely encased with the same skin. Therefore, it is foreseeable that one could misinterpret the separation of leg and foot that appears at the aft portion of the inventive ankle 20, and deem such separation to be more nearly in the nature of a forward and aft movement rather than a true tilting movement. However, the use of the selected terms should not and is not intended to detract from the invention. These terms are'employed only to more accurately describe the type of movement that would appear to result from the mechanism employed.

The pivot pin 32 mounted between the shoe 28 and the simulated leg 22 is connected with the leg 22 by the casing I along the confining surfaces of the elongated slots 34 defined in each of the casing sides 36 and 38. The ends of the pivot pin 32 extend laterally beyond the casing sides 36 and 38 as may be seen more clearly in FIG. 3. The pivot pin 32 is constantly urged yieldingly toward the lower portion of the slots 34 by spring means 54 that are removably mounted on the outer faces of the sides 36 and 38 of the casing.

The lower end finger 56 of each spring 54 extends through an opening that is provided in the ends of pivot pin 32 to constantly remain in engagement with the pin and to bear equally on opposite sides thereof to apply a force thereagainst to move the pin toward the lower portion of the slots 34. The upper finger 581 of the spring means 54 is engaged within a slotted opening of a spring securing bracket 60 mounted on the outer surfaces of the sides 36 and 38 of the casing.

Inasmuch as each spring 54 is fixedly mounted at its upper finger 58 to the spring bracket 60 secured to the casing sides, the coils thereof are permitted to expand so as to urge the lower spring finger 56 downwardly. This downward movement of the lower spring finger 56 is transmitted to the pivot pin 32 thereby constantly but yieldingly urging the pivot pin in displacement relative to the slot 34 of the casing and to the leg 22.

Mounted on the interior surface of the foot or shoe 28 is a base structure generally identified by the numeral 62. Although not shown in detail the base structure 62 is appropriately fixed in the shoe 28 so its lower surface plate is normally arranged parallel to a fiat or horizontal walking surface 66. The base structure 62 comprises forward and aft standards 68 and 70 that may be formed as an integral part of the surface plate 64, or subsequently secured thereto. The forward and aft standards 68 and 79 are of different heights, the aft standard 70 being slightly higher than the forward standard 68. Each standard is provided with a pivot collar 72 in which there is 4 adapted to be received for free pivoting movement a pivot and guide bracket 74. In FIG. 1 the forward standard 68 is cut away to show further details of the base 62.

The pivot and guide bracket 74 is provided at its forward and aft upper ends with pivoting protuberances 76, one of which is adapted to be smoothly and pivotly mounted in the collar 72 of the forward standard 68 while the other of which is adapted to be mounted for smooth pivotal movement within the collar 72 of the aft standard 78. Because of the difference in height of the standards 68- and 78, and the consequent relative heights of their respective collars 72, the pivoting protuberances 76 of the bracket 74 are accordingly arranged in an axial line that is angularly directed with respect to the walking surface 66. The bracket 74 is provided with a probe guideway that is elongated in length and has a central opening 7 8 which is directed substantially perpendicular to the surface plate 64.

Secured to the base structure 62 to form an integral part thereof for fixed movement with the foot or shoe 28 relative to the leg' 22 is an engaging or female clutch means 80. Referring to FIG. 3, it will be noted that the clutch means 80 is provided with an arcuate engaging surface directed laterally towards the opposite sides of the shoe or foot 28 while its forward and aft direction as seen in the drawings show the same directed at an angle inclined downwardly and forwardly toward the plate 60. The angle of inclination of the engaging means 80 is substantially the same as the angle of the axis of the pivoting.

protuberances 76 of the bracket 74.

The shoe or foot 28 is connected for forward and aft pivoting movement relative to the leg 22 about the common axis of pivot pin 32 by the forward and aft pivoting mechanism 30. The pivoting mechanism 30 comprises a shoe probe 82 that serves to connect the shoe with the pivot pin 32 for movement thereabout and for relative displacement with respect thereto and with respect to the leg 22.

The shoe probe 82 includes a pair of mirror image one-half probe members 84 and 86 that are positioned face to face along a separation line 88 (FIGS. 1 and 8). Each one-half probe member is mounted for free pivotal movement about the pin 32. They are held together along their downwardly extending arms 90 and 92 (FIG. 8) by corresponding surfaces of the probe guideway 78. Each half probe arm 90 and .92 is provided with one-half. of a pin receiving opening 94. Thus, when the probe arms 90 and 92 are positioned adjacent to each other within the guideway 78 their half pin receiving openings 94 therein will define the complete opening 94.

A clutch mounting pin 96 is placeable in the opening 94 and subsequently secured against displacement therefrom by a locking cross-pin 98. The cross-pin 98 is passed through aligned cross-pin receiving holes in each of the probe arms 90 and 92 while access for the application of the locking cross-pin into the probe arms and through the clutch mounting pin 96 is provided by an elongated opening 100 defined in the opposite sides of the probe guideway 78, as can be seen more clearly in FIGS. 1, 2, S, 8 and 10.

The clutch mounting pin 96 has secured thereto a male engaging member or clutch means 102. By virtue of the fact that the mounting pin 96 is fixed to the arms 90 and 92 by cross-pin 98, the clutch member 102' is caused to move with the shoe probe structure 82. The movement of the clutch means 102 is generally one of longitudinal displacement with respect to the female engaging means or clutch member 80 fixed to the base 62. The clutch means 102 is normally spaced for subsequent cooperative engagement with the shot clutch means 80 whose arcuate extent is substantially greater than that of the engaging means 102.

From what has been described one will readily recognize that the shoe or foot 28 .is capable of lateral pivotal movement about the protuberances 76 relative to the probe 82 and to the leg 22. The extent of this relative lateral pivoting movement of the shoe with respect to the structures connected therewith is limited by the sides of the shoe engaging with the sides of the simultated leg 22 that extends downwardly thereinto. Regardless of the lateral pivoting movement that the shoe 2% may perform with respect to the structure connected therewith, its enlarged arcuate clutch surface 80 will provide an engaging surface for the smaller clutch means 102 defining a part of the shoe probe 82.

The ability of the shoe or foot 23 to pivot laterally with respect to the leg 22 permits the wearer of the ankle to negotiate surfaces that may be inclined laterally. Thus the shoe or foot 28 is flexible. It is not absolutely fixed or limited for aligned movement with the leg hence, it will provide a support for the wearer on irregular surfaces or terrain.

Each one of the half shoe probe members 84 and S6 is provided with a circular clutching or restraining surface 1%. The surfaces 104 are ofifset laterally with respect to their respective downwardly extending arms 9i) and 92 so they may be positioned alongside the inner surfaces of the casing sides 36 and 38. This offset relationship results in the provision of a space between them in which there is mounted a leg probe 106. The leg probe 1% is mounted for pivotal movement about the pin 32 and for displacement with the pivot pin 32 relative to the leg 22 in a manner and for a purpose to be described.

Encompassing the aft portion of the leg probe 106 are laterally directed extensions 108 formed as integral parts of each one of the half probe members 84 and 86. The extensions 10%; are positioned adjacent to each other at center line 88. and are curved as at lit) to permit unobstructed pivoting movement of the leg probe 1% about the pin 32. The extensions W8 curve about the lower aft portion of the leg probe res and are angularly directed at 112 away from their respective probe arms 90 and 92 to terminate at legs 114.

The legs 114 of each of the half probe members $4 and 86 are secured together at their ends by suitable fastener means passing through aligned openings 116. Each one of the angularly directed portions 112 of each half probe members 84 and 86 has a mating half of an open ing I118 (see FIGS. 7 and 8) that is adapted to receive a bolt 120. The opening 118 defined by the mating halt probe members 84 and 86 is larger in diameter than that of the bolt 120 that is adapted to pass therethrough.

The bolt 120 is provided with an enlarged head 122 against which the cup-shaped washer 124 rests. The cupshaped washer 124- provides a seat for a coil spring 126 that abuts at its opposite end against the back or aft surface of the angularly directed portions 112 of the joined half probe members 84 and 86 of the shoe probe 82. The bolt 120 is threaded along at least a portion of its length to receive thereon an adjustable limit nut 128. The limit nut 128 is adapted to engage with the adjacent back portion 112 of the shoe probe 82 in the manner shown in FIGS. 6 and 10. The bolt 12% has mounted thereon a set of resilient buffers or cushioning washers 13b and 132 that are adapted to provide a cushion between the leg probe 106 and the portion 112 of the shoe probe when each of these members is urged toward the other by the coil spring 126 circumposed about the bolt 12%.

The shoe and leg probes 82 and 1% are constantly urged toward each other by the spring 126 bearing against the back surface of the portion 112 of the shoe probe 82 while the lower end of the coil spring applies an expanding force against the cup-shaped seat 124 mounted on the bolt 120. The forward end of the bolt passes through an enlarged opening 134 in the leg probe M6 and has an end nut 136 threadedly fixed thereon. The end nut 136 bears against a semispherically shaped bearing member 138 that seats within a corresponding hearing opening defined in the leg probe 1% in alignment with the opening 134. The bearing member 138 thus permits the bolt 120 to pivot with respect to the leg probe 196 without binding.

Hence, the exertion of the coil spring 126' against the back portion 112 of the shoe probe 82 and against the seat 124 positionedat the end of the bolt 120,- causes a force to be exerted equally against the leg probe 106 at 138 to move the leg and shoe probes toward each other. This movement is cushioned by the members and 132 positioned therebetween. It will be recognized that the leg and shoe probes 106 and 82 are susceptible also of relative movements as a result of the yieldable connection afforded by the spring 126 and attendant bolt structure. Thus, although the shoe and leg probes 82 and me are constantly biased and urged for conjoint rotation about the reference axis defined by the pivot pin 32, they are capable also of performing relative pivotal movements.

The forward and aft movement mechanism 30 which includes the shoe and leg probes 82 and 106 and the attendant structure therebetween and as described above, is adapted to pivot about the reference axis of the pivot pin 32 with the shoe or foot 23. This movement is accomplished because the downwardly extending joined arms 93 and 92 of the shoe probe 32 are mounted within the confines of the probe guideway 78 and are fixed for forward and aft pivotal movement therewith about the pivot pin and its axis when the shoe 28 moves-relative to the leg 22.

The engaging means or shoe probe clutch 102 is constantly urged upward away from corresponding coop crating engagement with the female engaging means or shoe clutch 8t) by a resilient or yieldable spring device. This spring device comprises the two spring members 140 and 1.42. The upper end of each of these spring members is engaged with an eye 144 that is formed as an integral part of the pivot and guide bracket 74. The lower end of each spring 140 and 142 is engaged in an eye 146 formed as a part of the clutch means 102. The function of the springs M0 and 142 is to bring the lower clutch eyes 14-6 upward toward the upper bracket clutch eyes 144 thereby constantly applying a force to the clutch member 1&2 to disengage the same from the shoe clutch 80.

The leg probe 106 has fixed thereto at its extreme upper narrow end 148 a male engaging means or clutch 150. The male engaging clutch 150 is adapted to engage with thegfemale clutch member 50 fixed for movement with the leg 22 by virtue of its securement to the casing 36, 38. The leg clutch 50 and the leg probe clutch 150 are inverted V shaped. In practice it has been found that this form of clutching engagement provides a guideway within which the means 50 and 150 cooperate thereby preventing their lateral relative displacement. However, it will be recognized that the specific shape here shown is not a limitation upon the concept'of the invention and any other suitable shape may be utilized to accomplish the desired purposes.

From what has been described thus far it will be noted that the forward and aft movement mechanism 30 permits relative forward and aft movement of the leg 22 and shoe or foot 28, about a common axis of the pivot pin 32; However, any forward and aft pivot movement of the shoe or foot 28 relative to the leg 22, when conforming to an irregular walking surface, will cause the forward and aft movement mechanism 30 to move about the axis of the pivot pin 32 with the shoe or foot by virtue of its engagement at 82 within the bracket 74.

Inasmuch as the leg probe 106 is resiliently urged for conjoint movement with the probe 82 by the combination of the spring 126 and the bolt 120 during the pivoting movement of the shoe 28 relative to the leg 22, its attend-' ant engaging clutch 150i is caused to move along the arc of the engaging clutch 50 fixed to the leg 22. Accordingly, the position :of the leg probe and its attendant en; gaging means 150 will vary with respect to the clutch 50 of the leg 22. However, the probe engaging means 150 will always remain between the walls of the clutch 50 and in a position for ready engagement therewith regardless of the relative forward and aft movement that the shoe 28 and leg 22 have with respect to each other.

If the leg probe engaging means 150 is engaged with the leg engaging means 50, arcuate movement of the probe relative to the leg 22 can be prevented. This engagement is accomplished by an action of relative displacement occurring between the engaging means 50 and 150 of the leg 22 and leg probe 106 respectively. Relative displacement can occur only at the pivot pin 32 by virtue of its lost motion connection with the elongated slot 34 defined in the sides 36 and 38 of the casing.

Thus, when it is necessary to prevent relative forward and aft movement between the leg 22 and the leg probe 106 and the related elements defining a part of the forward and aft mechanism 30, the wearer of the ankle need only apply his weight to the simulated leg 22. This weight need only be of sufiicient magnitude to overcome the opposing disengaged forces that are applied to the pivot pin 32 by the main spring members 54. When sufficient weight has been applied to the leg 22 by the wearer of the ankle to overcome the disengaged displacement force of the main spring 54, the leg 22 and the pivot pin 32 are relatively displaced toward each other.

Inasmuch as the leg probe 106' is mounted on the pivot pin 32, it too may be said to have relative displacement with respect to the leg 22. During the relative displacement, the leg 22 moves downwardly by virtue of the wearers weight applied to the same, the leg probe engaging means 150 is probed into clutching engagement and cooperation with the leg clutch 50. This engaged cooperation locks and secures the leg probe 106 and the leg 22 from relative movement about the axis of the pivot pin 32.

Quite obviously, the application of weight by the wearer of the ankle 20 must occur when the sole of the shoe or foot 28 is positioned on the walking surface 66 thereby resulting in a further displacement which occurs between the leg 22, the forward and aft mechanism and the foot or shoe 28. This Will be understood when it is recognized that as the leg is moved downward and is displaced with respect to the pivot pin 32, the pivot pin is also displaced with respect to the elongated slot 34 within which it is guidingly mounted. As the upper limits of the slots 34 are relatively displaced toward abutment with the pivot pin 32, the leg probe engages its clutch 50.

Continued application of weight on the leg 22 by the wearer now causes the leg and pivot pin to be displaced downward relative to the shoe or foot 28 positioned on the walking surface 66. This results in moving the pivot pin 32, abutting with the upper limit of the slots 34, downwardly towards the shoe or foot 28. Inasmuch as the shoe 28 is firmly positioned on the surface 66, the continued downward displacement of the pivot pin 32 causes the consequent downward displacement of the shoe probe 82 within the bracket guideway 73 toward the lower surface plate 64 until the shoe probe engaging clutch 102 is brought into cooperating engagement with the female shoe clutch 80. When such engagement results the shoe 28 and mechanism 30 are clutchingly engaged and prevented from further lateral or forward and aft pivotal movement.

At this time one may readily understand that if the shoe or foot 28 is positioned on a surface that is laterally inclined as in FIG. 11, the sole of such shoe will conform to the inclination of the surface 66 by virtue of the pivotal movement permitted at the cooperating collar 72 and protuberances 76. The greater extent of the laterally directed arcuate surface of the shoe engaging clutch 80 as seen in FIGS. 1, 3 and 11 insure that the same will be engaged by the shoe probe clutch 1G2 when'negotiating all reasonably laterally inclined surfaces 66. The

clutches 8t) and 102 will remain engaged and limited from further relative movement until such time as the wearer releases or removes his weight from the leg 22.

When the wearer subsequently removes his weight from the ankle structure 20, the spring members 54 acting between the leg structure 22 and the mechanism 30 at the pivot pin 32, and the spring means 140 and 142 acting between the clutch 102 of the mechanism 30 and the base of the shoe 28, will apply a force to relatively displace the structural elements with which they cooperate to return the same to their normal disengaged free moving positions. At this time, to further comprehend the operation of the artificial ankle 20, it is' noted that gravity would normally return the pivot pin 32 into abutment with the lower portions of the elongated slots 34 without the application of pressure by the main springs 54 on the pivot pin.

The shoe 2% will fall and be displaced relative to the leg 22 and to the pivot pin 32 and also to the mechanism 36 simultaneously with the removal of the wearers weight without the application of force applied by the displacement springs 140 and 14-2. However, in practice it is found that the addition of the spring mechanisms contribute to the more rapid operation of the structures with which they are connected and keeps them separated when initiating a step.

Referring now to the drawings, and more particularly to FIG. 9, it is noted that the engaging clutches 150 of the leg probe 106 and 102 of the shoe probe 82 are shown in their normally disengaged displaced relationship with respect to their cooperating leg and shoe clutches 50 and respectiyely.- The sole of the shoe 28 is positioned flat on the walking surface 66 while the simulated leg 22 has a relative ankle of repose which indicates that the wearer thereof is sitting or reclining in a slouching position.

It is to be noted here that by virtue of the operation of the mechanism 30 the sole of the shoe 28 is capable of being placed flat upon the surface 66 while the leg 22 stretched outward at an extreme angle in much the same manner that a human ankle will permit one to position the sole of his shoe fiat upon the ground while sitting in an extreme reclining positon. This is a conspicuous feature in the present invention because it permits the amputee wearer to sit in the same manner as any one else without distinguishing himself as one who is afilicted with a false ankle or prosthesis.

At this time it will be recognized that the weight of the wearer is relaxed and removed from the ankle structure 20. To rise from this position it is generally the practice for a person with a normal ankle to retract his legs back to a position wherein the same are near a position perpendicular to the surface 66. Such person with a normal ankle then rises by placing his weight directly upon his legs. This weight is transmitted to the ankle and to the foot and thence to the surface 66.

In like manner a wearer of the prosthetic ankle 20 performs the same procedure as he moves his legs from the position shown in FIG. 9 to that shown in FIG. 5. As he retracts his simulated legs 22, with the sole of the shoe 28 still flat on the surface 66, there is a relative pivotal movement that occurs between the shoe and the leg about the common axis of the pivot pin 32. During this movement there is a further relative arcuate movement that occurs between the leg probe 106 and the arcuately shaped leg engaging clutch 50. While the leg 22 is brought to a position approximating the perpendicular as in FIG. 5, the leg probe 106 remains with the portion 112 of the shoe probe 82 and at an angle with respect to the perpendicular because of the resilient force applied thereby by the spring and the bolt connection 126 and 129.

As the wearer stands his weight is applied to the leg 22 and overcomes the opposition of the springs 54, and 14-2 to bring the engaging means and 5t), and 102 and 80 into clutching cooperation. When this clutching cooperation occurs the shoe and leg are yieldingly locked to the. forward and aft mechanism 30 by virtue of the spring and bolt connection 126 and 120. There is now permitted a further relative forward and. aft pivoting movement between the leg 22 and the shoe 28 about the axis of'the pivot pin-32.

To understand this ability of further movement, attention is directedto thebolt structure 120. With the leg probe clutch 1'50 engaged with the leg clutch S0, and with the shoe probe clutch 102 engaged with the shoe clutch 80, the leg probe will now move about the axis of the pivot pin 32 with the simulated leg 22 when his moved further into substantially perpendicular position relative to the walking surface 66 while the shoe 28 remains fixed solidly andimmovable. on the walking surface 66. The leg probe thus pivots with the leg 22-about the axis ofthe pivot pin 32 pulling the bolt 120 and seat 124 against the opposition of the coil spring 126fand causing the coil spring to contract in length. As the leg probe moves progressively away from the cushioning washers 130 and 132 to assume aposition such as that shown in FIG. 6, the spring 126 is contracted further.

With the wearer now standing in the upright position as shown in FIG. 6, the adjustable limit nut 128 is brought into abutment with the back surface of the portions 112 of the shoe probe 82. The predeterminately adjustable space between the. nuts 128 and 136 on the bolt 120 thus serves to limit the extent-of-relative pivotal movement that the leg probe 106 can have with respect to portions 112 of the shoe probe 82. This in turn' delimits the relative pivoting movement that the leg 22 may perform with respect to the shoe 28.

To' provide the wearer with the necessary feeling of solidity and support while standing still in the upright position or prior to taking hisnext step, and to be sure that he is given this vertical supportagainst forward and aft swaying motion, there is provided pawl structure 152. The pawl 152 is pivotally mounted at 154 in an opening of the probe 106 and directed'aft' toward the legs- 114 of the half probe members 84 and 86, of the shoe probe 82. The pawl is widened at its aft portion 156 and falls freely to engage with the forward surface of the angularly directed portions 112 of the half probe members 84' and 86 as in FIG. 6, as the leg probe 106 pivots suihciently away from portions 112. The center of the pawl has a recessed locking surface 158 (FIG. 1) and a stop surface 160. The locking surface 158 is adapted to engage with the forward surface of the portions 112 while the stop surface 166 rests uponh'ardened bearing plates 162 ('FIGS. 1, 6 and 10) inset on the legs 114 so that the wear of the locking pawl against the half members 84 and 86' will not chip or deface the same.

The locking pawl member 152 projects laterally on opposite sides of the probe 106 for locking movement in the Space that is defined between the facing surfaces of the circular clutches 104. The lockingcooperation of the pawl 152 with the portions 112, within the limited movement afforded by the predetermined adjustment of the nuts 128 and 136, serves to lock the mechanism 30 and consequently lock the leg 22 and shoe 28 from relative forward and aft pivotal movement. This looks up the ankle 20 and provides the wearer with a rigid, non-yielding support.

For the wearer ofthe artificial ankle 20 to now take a new walking step from the upright position, he need only lift his leg 22 to remove his weight from the ankle. Immediately upon the removal of the wearers weight from the ankle, the pivot pin 32and slot 34 are relatively displaced into a position as in FIG. 5. All of the. clutches are disengaged and displaced by the spring devices 54, 140, and 142. Thus, the shoe .28 is now free, again: topivot forward and aft about the axis of the pivot pin 32'while the leg 22 is extended forward for a new step. During this time; the leg probe clutch 150 and. the leg clutch, 50 "have; relative. arcuate: movement with. the clutch ISOremaining within the; confines 1d of the female clutch 50 for ready re-engagement therewith.

As the pivot pin 32 moves down within the slot 34 it is necessary to disengage the lock pawl 152, see FIG. 12. This is accomplished by the provision of a pair of trippers 164, each secured to the inner surface of a respective casing side 36 and 38. The two trippers 164 are identical in structure. They each have an arcuate upper surface 168 that serves to engage and lift the pawl out of engagement with the portions 112 of the shoe probe 82 when the leg 22 and the casing sides to which the trippers are attached are lifted and displaced upwardiy relative to the pivot pin 32. The surface 168 has a substantial arcuate length to insure its constant co-operation with the underside of the locking pawl 152 through all angles of relative movement that may occur between the leg probe 106 and the leg 22. Therefore, as the leg 22 and its casing are lifted, the tripping surface 168 of the tripper 164 forcibly pushes up and releases the locking engagement of the pawl with the poftions 112.

During this time, it is important that the leg and shoe have free relative forward and aft pivoting movements, but it is necessary to prevent the shoe from freely flopping or pivoting about the axis of the pivot means 32 limitlessly or needlessly. There must be some control on the movements of the foot or shoe 28 so that the toe portion thereof will not have the tendency always to fall toward the ground without control.

To this end, the tripper means 164 is provided with a pair of forward and aft downwardly extending limiting means or fingers 170 and 172. Cooperating with the fingers 170 and 172 are respective forward and aft restraining members 174 and 176, see FIGS. 7 and 8'. There are two sets of members 174 and 176, one each for cooperation with the circular clutches of the half shoe probe members 84 and '86.

The set of forward and aft restraining members 174 and 176 are pinned together at their lower portions 178 to encircle about the surfaces 104 of each of the members 84 and 86. The upper ends of the members 174 are provided with limit fingers 180. The upper ends of the members 176 are similarly provided with limit fingers 182. The member 174 has a boss 184. A shaft 186 passes through the boss 184 and through the enlarged portion of the member 176. A nut 188 (FIG. 7) adjustably limits the degree of separation of the members 174 and 176 about the pin 178 while a spring 190 provides a yieldable force to move the two members toward each other and into engaging cooperationcircumferentially about their restraining surfaces 104.

Referring to FIG. 3 of the drawings, it will be. noted that the circumference of each of the restraining; urfaces 104 is provided with V-shaped grooves. In like manner the corresponding engagingportions of each of the sets of restraining members 174 and 176 may have inverted V-shaped engaging surfaces to insure that they will be constantly'seated in and ready for engagement with their respective clutch 104. However, it is to be understood that the shape or the cooperative engaging portions of members 174, 176 and 104 may be varied without detracting from the concept of the invention.

From what has been described with respect to the restraining and limiting structures shown in FIGS. 7 and 8 it will be recognized that the lost motion cooperation between the sets of'fingers 170, and 172, 182 will allow free but limited pivotal movement of the mechanism 30 and Shoe 28 relative to the leg 22 when the weight of the wearer is removed from the the ankle 20. Thiswill permit the sole of the shoe to adjust initially to minor irregularities in the surface 66 before taking a new step. Thereafter, any further relative movement that may be necessary to negotiate a steep downwardly or upwardly inclined. surface as shownin FIG.

11 10, may be accomplished by overcoming the clutching engagement of the members 174 and 176 in 104.

The restraining force applied by the set of members 174 and 176 on the Surface 104 is controlled by the force of the spring 190. Since the restraint required to prevent unlimited and uncontrolled flopping movement of the shoe 28 is not great, the force of spring 1% is light. When the sole of the shoe is initially placed upon an inclined surface 66 as in FIG. 10, the slight foot pressure applied to the shoe will be suflicient to overcome the force of the restraining spring on the set of engaging members 174 and 176 acting on the member 104. In consequence, the shoe probe structure 82 and its clutch 104 will move relative to the members 174 and 176 that are limited from rotation therewith by the fingers 180 and 182 cooperating with fingers 170 and 172 respectively that are fixed to the casing. Accordingly, the mechanism 30 moving relative to the fixed fingers 170 and 172, allows the shoe to conform to the contour of the walking surface prior to the wearer applying his weight to the ankle 20.

After the sole of the shoe is properly positioned on the surface 66, the wearer of the ankle 20 then performs the same stepping operation as previously described and depicted in FIG. 10. In such case he need only apply his weight to the ankle in the same manner that a normal person does. This weight serves to overcome the force of the springs 54, 140 and 142 to displace the shoe and leg relative to each other. Thereafter the leg'and shoe clutches 50 and 80 are engaged with their respective probe clutches 150 and 102 while the leg continues to pivot towards its perpendicular position. As the leg probe 106 is separated from the portions 112, the pawl 152 automatically will fall into locking position as in FIG. 10.

At this point it will be noted that the leg probe clutch 150 has assumed a position along the arcuate extent of the leg clutch 50 different from that shown in FIGS. and 6. To understand this it will be recalled that the leg probe 106, forming a part of the mechanism 30, pivots with the mechanism relative to the limiting fingers 170 and 172 that are fixed to the leg casing during the initial placement of the shoe on the inclined surface 66. Therefore, as the mechanism 30 pivots with respect to leg 28 and its attendant clutch 50 fixed thereto, the leg probe clutch 150 will move arcuately along the length thereof for ready engagement with the same.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

I claim:

1. In an artificial ankle, a pivot, a simulated leg including engaging means fixed for movement therewith, means connecting said leg with said pivot for forward and aft relative pivoting movement and relative displacement, a probe pivotally mounted on said pivot and having means releasably engageable with said leg engaging means during predetermined relative displacement of said leg and pivot, and means connected with said pivot biasing the same against said relative displacement.

2. In an artificial ankle, a simulated leg, a shoe positioned beneath said leg and movable relative thereto, a casing, means connecting said casing for movement with said leg, said casing having engaging means secured for movement therewith, a base in said shoe having engaging means secured for movement therewith, pivot means displaceable relative to said casing, and means movable with said shoe relative to said leg about said pivot means and connecting said pivot means with said base, said movable means including means to releasably engage said base engaging means during predetermined relative displacement of said casing and pivot.

3. In an artificial ankle, a simulated leg and a shoe each including engaging meansfsaid leg and shoe having relative forward and aft pivoting movements, pivot means about which said relative pivoted movements are performed, means connecting said pivot means and leg for said relative pivoting movement and for relative displacement, means connecting said pivot means and shoe for said relative pivoting movement and including means engageable with said shoe engaging means, and probe means on said pivot means including means engageable and disengagea-ble with said leg engaging means in accordance with the relative displacement of said leg and pivot means.

4. In an artificial ankle, a shoe having engaging means, a simulated leg, a pivot, means connecting said shoe to said pivot for movement thereabout, said shoe connecting means having engaging means and being operable to engage said shoe engaging means, means mounting said pivot to said leg for relative engaging and disengaging displacement and for relative pivotal movement, said mounting means including engaging means fixed for movement with said leg, and probe means pivoted on said pivot and having means engageable with said engaging means fixed for movement With said leg during said engaging displacement and disengageable from said leg engaging means during said disengaging displacement, said shoe connecting means being operable to engage its engaging means with said shoe engaging means during said engaging displacement and to disengage said shoe engaging means during said disengaging displacement.

5. In an artificial ankle having a simulated leg and shoe 7 relatively movable forward and aft to simulate human ankle movements, a pivot, leg probe means movable about said pivot and engageable with said leg for movement therewith, shoe probe means connected with said shoe for movement therewith and about said pivot in accordance with the forward and aft movements of said shoe relative to said leg, and means between said shoe probe and leg probe means to conjointly move the same about said pivot and to permit relative movement therebetween.

6. In an artificial ankle having a simulated leg and shoe relatively movable forward and aft to simulate a human ankle, pivot means, leg probe means and shoe probe means mounted for movement about said pivot means, said shoe probe means being connected with said shoe for movement therewith about said pivot means in accordance with the forward and aft movements of said shoe relative to said leg, and means connecting said leg and shoe probe means for conjoint movement about said pivot, said leg probe means having means engageable with said leg for movement therewith about said pivot means and relative to said shoe probe means in accordance with the relative forward and aft movements of said shoe and leg, said means connecting said leg probe and shoe probe means for conjoint movement being yieldable to permit said leg probe and shoe probe means to move relative to each other with said leg and shoe respectively when said leg probe means is engaged with said leg.

7. In an artificial ankle having a simulated leg and shoe relatively movable forward and aft to simulate the movements of a human ankle, a pivot about which said leg and shoe have said relative forward and aft movements, leg probe means and shoe probe means. said shoe probe means being connected with said shoe for forward and aft movements about said pivot, said leg probe and shoe probe means each including means engageable with said leg and shoe respectively for conjoint movement therewith, means operative between said leg probe and shoe probe means to move said leg probe means about said pivot with said shoe probe means and to permit predetermined relative pivoting movement therebetween when the same are engaged for conjoint movement with said leg and shoe respectively, and means between said leg probe and shoe probe means to lock the same in said position I of predetermined relativepivoted movement.

8. In an artificial ankle having a simulated leg and shoe thatare relatively movable forward and aft to simulate the movement of a human ankle, a forward and aft movement mechanism comprising a shoe probe connected for forward and aft movement with said shoe relative to said leg, a leg probe movable with said shoe probe and having means engageable with said leg for conjoint movement therewith relative to said shoe, means between said leg and shoe probesto constantly urge said leg probe for movement with said shoe probe and yieldable to permit said leg probe to move forward and aft relative to said shoe probe when said leg probe is engaged with said leg, and means operable between said leg and shoe probes to lock the same from relative forward and aft movement.

9. In an artificial ankle for amputees having a leg and shoe that have relative pivotal forward and aft movement, a casing fixed in said leg and having clutch means, an elongated slot in said casing, pivot means movable along said slot, a base in said shoe and having clutch means, a forward and aft movement mechanism between said shoe and leg including means pivotally mounted for movement about said pivot means and movable with said pivot means along said slot to permit relative movement between said leg and shoe when the wearer of the ankle removes his weight therefrom, clutch meanson said pivotally mounted means for clutching engagement with said casing clutch means and said shoe clutch means when the wearer exerts his weight on the ankle to move said pivot means along said -slot, means included in said mechanism to lock said leg and shoe together after a predetermined relative forward and aft pivoting movement when said clutch means are engaged, and means cooperating with said lock means to release the same when the wearers weight is removed from the ankle.

10. In an artificial ankle for amputeeshalving a leg and shoe relatively pivotable forward and aft, a pivot, said leg and shoe having relative displacement toward each other when the wearer of the ankle applies his weight to the same and away from each other when the wearer removes his weight from the same, a forward and aft 14 shoe away from each other when the wearers weight is removed from the ankle.

12. In an artificial ankle for anamp utee, a leg and shoe, a pivot about which said leg and shoe have relative movements, a casing connecting said leg with said pivot, probe means connecting said shoe with said pivot, limit means on said casing for movement therewith and with said leg, and restraining mean-s cooperating with said limit means to restrain the relative movement of said shoe and leg to a limited extentand being movable with said limit means and leg relative to saidshoe.

13. In an artificial ankle for an amputee, a leg and shoe, pivot means, a casing fixed to said leg and connecting said leg with said pivot means for pivotal movement and relative displacement, said casing having clutch means fixed thereto, shoe probe means fixed to said shoe and connecting said pivot and shoe for relative pivotal movement and relative displacement, said probe means and shoe having engageable clutch means, a leg probe pivoted about said pivot means and having clutch means engageable with said casing clutch means, said shoe and leg having free relative forward and aft pivotal movement, limit means on said casing, restraining means having a lost-motion cooperation with said limit means to apply a restraint on the extent of free relative pivotal movement of said leg and shoe, means to pivot said leg probe with said shoe probe about said pivot means and to permit predetermined relative pivotal movement therebetween when said probe clutch means are engaged with said casing and shoe clutch means respectively, said pivot means being displaceable toward said shoe and leg when the wearer applies his weight to the ankle to engage said leg.

said lock means.

movement mechanism on said pivot including means cooperable with said leg and shoe to limit the forward and aft relative pivoting movement of said shoe and leg when the wearer's weight is applied to the ankle and to permit desired forward and aft relative movement when the wearer removes his weight from the ankle, means to lock said shoe and leg together after the same have reached their limited forward and aft relative movement, and means cooperable with said lock means to release the same in response to the relative displacement of said leg and shoe when the wearer removes his weight from the ankle.

11. In an artificial ankle for amputees wherein the leg and shoe have relative forward and aft pivotal movement, a pivot about which said leg and shoe move and are relatively displaceable toward and away from each other in accordance with the application or the removal of the Wearers weight on the ankle, a forward and aft movement mechanism on said pivot including means to limit the forward and aft relative pivotal movement of said shoe and leg when the Wearers weight is applied to the ankle and to permit desired forward and aft relative pivotal movement of said leg and shoe when the wearer removes his weight from the ankle and means to lock said shoe and leg from relative pivotal movement when the same have reached their limit of forward and aft relative pivotal movement, meansconstantly urging said leg and shoe for relative displacement away from each other and yieldable in response to the applied weight of the wearer, and tripper means on said leg to release said lock means in response to the relative displacement of said leg and 14. In an artificial ankle as in claim 13, a base in said shoe connected with said shoe probe means for lateral pivotal movement of said shoe relative to said shoe probe means and including said shoe clutch means, the engagement of said shoe clutch means and said shoe probe clutch means serving to secure the same from same relative lateral pivotal movement.

15. In an artificial ankle for an amputee, a pivot, a leg and shoe having relative lateral pivotal movements and forward and aft relative pivotal movements about said pivot, a forward and aft movement mechanism connecting said leg and shoe with said pivot for said relative forward and aft pivotal movement and including means displaceable relative to said leg to lock the same from said relative forward and aft movements, and pivot means in said shoe permitting lateral pivotal movement of said shoe relative to said leg and having means displaceable relative to said mechanism and engageable with said mechanism to restrict the relative lateral pivotal movement of said leg and shoe.

16. In an artificial ankle for an amputee, a shoe, a leg, a mechanism between said leg and shoe to permit relative forward and aft pivoted movement of said shoe and leg about a common axis, a base connecting said mechanism and shoe to permit relative lateral movement of said shoe relative to said leg, said base and mechanism each including means relatively displacea'ble :in response to the application of a predetermined weight on the leg and engageable to prevent said relative lateral movement, and said mechanism including means cooperable with said leg to prevent said relative forward and aft pivotal movement.

f 17. In an artificial ankle for an amputee, a leg, a shoe,

1 5 a mechanism to permit and control relative forward and aft pivoting movements of said leg relative to said shoe, a base in said shoe connecting the shoe with said mechanism for lateral pivotal movement relative to said leg and being displaceable with respect to said mechanism, means on said base and mechanism engageable to prevent said relative lateral pivotal movement, engaging means on said leg, means included in said mechanism engageable with said leg engaging means to prevent said relative forward and aft pivoting movements of said leg and shoe, and means connecting said leg and mechanism for relativ displacement, said mechanism engaging means engaging said leg and base engaging means when the amputee applies his weight to the ankle to displace said leg and base relative to said mechanism and to release said engagement when the amputee removes'his weight from the ankle.

18. In an artificial ankle as in claim 17, and means between said leg and said mechanism and said base and said mechanism opposing the engagement of said engaging means and said relative displacement and yieldable upon a predetermined application of weight by the amputee to permit said engagement.

References Cited in the file of this patent UNITED STATES PATENTS 2,692,990 Schaefer Nov. 2, 1954 2,853,712 Bach 7 Sept. 30, 1958 2,863,684 Carroll Dec. 9, 1958 

